共查询到20条相似文献,搜索用时 15 毫秒
1.
Czeslawa Orlewska Rafat M. Shaker Martin Dees Hans-Hartwig Otto 《Monatshefte für Chemie / Chemical Monthly》2000,6(4):889-893
The reaction between push-pull olefins of the acyloxymethylidene-malononitrile type and α, β-unsaturated hydrazones affords selectively 5-alkyl-2-cyano-6-(N′,N′-dimethylhydrazono)-hexa-2,4-dienenitriles. No [4+2]-cycloaddition products were detected. The structure elucidation of the obtained compounds and possible reaction mechanisms are discussed. 相似文献
2.
T. A. Koval'chuk N. M. Kuz'menok A. M. Zvonok 《Chemistry of Heterocyclic Compounds》2005,41(10):1237-1244
It was established that the reaction of 3-aryl-1-(2-methyloxiran-2-yl)prop-2-en-1-ones with tosylhydrazine leads to 3-[(E)-2-arylvinyl]-4-methyl-1-tosyl-1H-pyrazoles
and 3-aryl-1-(2-methyloxiran-2-yl)-3-tosylpropan-1-ones. The latter are formed as a result of rearrangement of the intermediate
hydrazino alcohols and/or addition of p-toluenesulfinic acid during reductive degradation of the tosylhydrazine. It was shown
that the reaction of 3-aryl-1-(2-methyloxiran-2-yl)-3-tosylpropan-1-ones with an excess of tosylhydrazine leads to 3-(2-aryl-2-tosylethyl)-4-methyl-1-tosyl-1H-pyrazoles.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1481–1489, October, 2005. 相似文献
3.
Atef M. Amer 《Monatshefte für Chemie / Chemical Monthly》2001,132(7):859-870
Summary. The synthesis of a series of disubstituted (4-aminocinnolin-3-yl)-aryl-methanones from aryl-hydrazonomalononitrile in a one-step
procedure is described. Cyclocondensation of (4-amino-6,8-dimethyl-cinnolin-3-yl)-phenyl-methanone with malononitrile, diethylmalonate,
and dimethylacetamide-dimethylacetal gave the corresponding pyrido[3,2-c]cinnoline derivatives. Treatment of (4-amino-6,8-dimethyl-cinnolin-3-yl)-phenyl-methanone with triethyl-orthoacetate under
reflux readily afforded the corresponding imidoester which underwent cyclization to a pyrido[3,2-c]cinnoline derivative. This starting compound could also be annelated to the corresponding 1,2-dihydro-4-aryl-2-oxo-pyrido[3,2-c]cinnoline derivatives via the (4-acetamidocinnolin-3-yl)-aryl-methanones. Chemical and spectroscopic evidences for the structures of the new compounds
are presented. The effect of three of the compounds against sixty cancer types was tested.
Received November 27, 2000. Accepted December 4, 2000 相似文献
4.
In the present study the derivatization of two water-soluble and synthetic polymers, such as α,β-poly(N-hydroxyethyl)-DL-aspartamide
(PHEA) and α,β-polyasparthydrazide (PAHy), with glycidylmethacrylate (GMA) is described. This reaction allowed the introduction
of double bonds in the macromolecular chains of PHEA and PAHy in order to make easier the crosslinking by a radical mechanism.
Different parameters affected the reaction of derivatization, such as reaction pH, GMA concentration and reaction time. As
far as PHEA is concerned the amount of GMA linked to the polymer increased until reaching a plateau. On the contrary, the
reaction of PAHy with GMA proceeded with a zero order kinetics and the GMA amount in the polymer increased regularly. Some
aqueous solutions of PHEA-GMA and PAHy-GMA copolymers at various GMA content were submitted to gamma radiation processing,
thus obtaining crosslinked structures. The derivatization of PHEA and PAHy with GMA was a convenient method to introduce insaturations
in their chains and it allowed to obtain gels at lower doses with respect to the starting polymers.
Received: 2 April 1996 Accepted: 30 June 1996 相似文献
5.
Annegret Tillack Harald Trauthwein Christian G. Hartung Martin Eichberger Stephan Pitter Achim Jansen Matthias Beller 《Monatshefte für Chemie / Chemical Monthly》2000,131(12):1327-1334
Summary. The oxidative amination of styrene with secondary amines in the presence of cationic rhodium catalysts yields regiospecifically
the corresponding anti-Markovnikov enamines. Styrene as the hydrogen acceptor gave concomitantly ethylbenzene. In the presence of 1,5-cyclooctadiene (cod) preferential reduction to cyclooctene takes place. The addition of cod reduces the rate of the reaction, but also the amount of ethylbenzene produced. Here, for the first time the ratio of enamine:
ethylbenzene is > 1, which is favourable in case of more expensive styrene derivatives. A screening of various ligands for
oxidative amination reveals that hemilabile 2-(ω-phosphino-n-alkyl)-pyridines are superior ligands for this reaction compared to simple alkyl and aryl phosphines.
Received May 30, 2000. Accepted July 11, 2000 相似文献
6.
Summary. Photocatalytic ring opening of α-epoxyketones by 2,4,6-triphenylpyrylium tetrafluoroborate in acetone resulted in the formation
of 1,3-dioxolanes as major products through C–O bond cleavage and the formation of alcoholic by-products through C–C bond
cleavage. The type and nature of the substituent affects the rate of ring opening.
Received June 19, 2001. Accepted (revised) November 28, 2001 相似文献
7.
Yanhe Huang 《Monatshefte für Chemie / Chemical Monthly》2000,131(5):521-523
Summary. Except for the catalyst and the temperature, the nature of the solvent also affects the aldol condensation, favouring α,β-unsaturated
carbonyl compounds in alcoholic solvents or β-hydroxyl carbonyl compounds in tetrahydrofuran.
Received November 22, 1999. Accepted (revised) December 21, 1999 相似文献
8.
Taking into account the uncertainty of measurement when assessing compliance of a given sample with compositional specifications
or statutory limits is an open question. Rigorous assessment should be performed within the signal domain, and by considering
both α and β errors. Working within the concentration domain through a calibration function, which is affected by additional
experimental uncertainties, involves a different degree of uncertainty and can sometimes lead to unreliable verdicts. The
matter is discussed, and illustrated with the aid of some worked examples, each using multiple simulated data sets, obtained
by adding an arbitrarily chosen Gaussian noise to representative response/concentration functional relationships.
Received: 12 October 2000 Accepted: 12 July 2001 相似文献
9.
E. D. Matveeva T. A. Podrugina A. S. Pavlova A. V. Mironov N. S. Zefirov 《Russian Chemical Bulletin》2008,57(2):400-405
The nucleophilic substitution in mixed phosphonium-iodonium ylides was investigated. The iodonium group is replaced by such
S-containing nucleophiles as the thiocyanate anion or thiourea, as well as by halide ions. The structure of the reaction product
with the thiocyanate ion was established by X-ray diffraction. A one-pot process involving the nucleophilic substitution and
the Wittig reaction was developed.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 391–395, February, 2008. 相似文献
10.
Siavosh Mahboobi Markus Koller Dieter Schollmeyer 《Monatshefte für Chemie / Chemical Monthly》2000,131(4):383-392
Summary. The racemates of the rubiacea alkaloid Chrysotricine (1) and its diastereomer are synthesized from the isomeric mixture of linalyl oxides 3 and tryptamine in six steps, followed by separation of the diastereomers.
Received November 11, 1999. Accepted November 25, 1999 相似文献
11.
Babasaheb P. Bandgar Lav S. Uppalla Vaibhav S. Sadavarte 《Monatshefte für Chemie / Chemical Monthly》2000,131(9):949-952
Summary. Syntheses of α,β-unsaturated nitroalkenes have been carried out under mild condition using morpholine adsorbed on silica
gel as a novel catalyst.
Received February 14, 2000. Accepted March 28, 2000 相似文献
12.
Substituted hexahydroindazoles were obtained by the reaction of 6-arylidene-2-furfurylidene-cyclohexanones with phenylhydrazine.
It was concluded by means of the NMR spectra that azacyclization takes place regioselectively with participation of the arylidenecyclohexanone
fragment.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 986–990, July, 2005. 相似文献
13.
Magdolna Solymár Márta Palkó Tamás Martinek Ferenc Fülöp 《Monatshefte für Chemie / Chemical Monthly》2002,133(11):1423-1430
Summary. The reactions of 1,2,3,4-tetrahydro-β-carboline-1-carboxylic acid and its ethyl ester with alkyl and aryl isothiocyanates
under mild conditions resulted in the corresponding thiohydantoin-fused tetrahydro-β-carbolines. Treatment of the ethyl ester
with isocyanates furnished ethyl 2-alkyl- or arylcarbamoyl-1,2,3,4-tetrahydro-β-carboline-1-carboxylates which were transformed
to hydantoin-fused tetrahydro-β-carbolines. The structures of the thiohydantoin compounds, involving two conformers and the
presence of keto-enol tautomerism, were determined by NMR spectroscopy.
Corresponding author. E-mail: fulop@pharma.szote.u-szeged.hu
Received February 2, 2002. Accepted (revised) March 4, 2002 相似文献
14.
Vesna Kuntić Dusěan Malesěev Zorica Radović Vladana Vukojević 《Monatshefte für Chemie / Chemical Monthly》2000,131(7):769-777
Summary. In the present work, rutin (3,3′ ,4′ ,5,7-pentahydrohyflavone-3-rhamnoglucoside) was determinated via a complexing reaction with a titanyloxalate anion. K2[TiO(C2O4)2] and rutin react in 50% ethanol forming a 1:2 complex in a pH range from 4.00 to 11.50, in which the TiO(C2O4)2
2− ion is linked to rutin through the 4-carbonyl and 5-hydroxyl group. The thermodynamic stability constant log β2
0 of the complex is determined to 10.80 at pH = 6.50. The change of the standard Gibbs free energy Δ G0 amounts to −61 kJċ mol−1, indicating that the process of complex formation is spontaneous. The optimal conditions for the spectrophotometric determination
of microconcentrations of rutin are at pH=6.40 and λ= 430 nm, where the complex shows an absorption maximum with a molar absorption coefficient a
430=(60±2)ċ103 dm3ċ mol−1ċ cm−1. The method is applied rutin determination from tablets.
Received January 4, 2000. Accepted (revised) February 17, 2000 相似文献
15.
Krystyna Bogdanowicz-Szwed Artur Budzowski 《Monatshefte für Chemie / Chemical Monthly》2001,132(8):947-957
Summary. The hetero-Diels-Alder reaction of 3-dimethylamino-1-(2-thienyl)-2-propene-1-thione (diene) with substituted β-nitrostyrenes, as well as maleic
and fumaric acids (dienophiles) yielded 3,4-dihydro-2H-thiopyran derivatives. The treatment of some of those cycloadducts with acetic acid caused elimination of dimethylamine,
affording stable 2H-thiopyrans. A reaction of the diene with maleic anhydride furnished a cycloadduct which underwent spontaneous rearrangement
to form an N,N-dimethylamide derivative. Cycloadditions of the diene to maleimide, N-phenylmaleimide, maleic acid monoanilide,
diethyl maleate, fumarate, and butenolide carried out in the presence of acetic anhydride were followed by elimination of
dimethylamine under formation of stable 2H-thiopyran derivatives.
Received February 19, 2001. Accepted (revised) March 12, 2001 相似文献
16.
The iodine-azide reaction induced by eight thiosemicarbazones was investigated. Inducing properties of thiosemicarbazones
are different and depend on the parent carbonyl compound used for synthesis. The inductor coefficients of the examined thiosemicarbazones
vary from 61 to 176. Optimum conditions for the determination of microamounts of thiosemicarbazones are given. The detection
limit for the determination by the back-titration method depends on the inducing activity and is 0.9 μg for phenyl-thiosemicarbazones
and 2 μg for diethyl-thiosemicarbazone in a 5-mL sample, and this corresponds to a concentration of 0.9 × 10−6 mol/L and , respectively. The automatic titration with the diluted iodine solution decreases the detection limit to about 50 ng in a
10-mL sample.
Received October 28, 1998. Revision April 9, 1999. 相似文献
17.
Ahmad S. Shawali Rifaat H. Hilal Said El-Sheikh 《Monatshefte für Chemie / Chemical Monthly》2001,132(6):715-720
Summary. Bis-hydrazonoyl chlorides react regioselectively with pyrimidine-2-thiones, which contain a masked thiourea residue, to give
the hitherto unknown annelated 2,3-bis-arylhydrazono-thiazoles and 3,3′-bis-1,2,4-triazoles. Reaction of bis-hydrazonoyl chlorides with 2-methylthio derivatives gave only 3,3′-bis-1,2,4-triazoles.
Received October 4, 2000. Accepted (revised) December 20, 2000 相似文献
18.
The uncertainty affecting analytical measurements has to be taken into account when evaluating compliance of suspect matrices
to legislative limits. To this aim Type 1 and 2 errors must be considered. This necessarily leads to the evaluation of the
minimum detectable inadmissible signal, from which the minimum detectable inadmissible concentration can be obtained. The
signal of suspect matrices thus has to be compared with the minimum detectable inadmissible signal. This paper aims to discuss
practical problems involved in the comparison. 相似文献
19.
Jozef Saloň Viktor Milata Nadežda Prónayová Ján Leško 《Monatshefte für Chemie / Chemical Monthly》2000,131(3):293-299
Summary. Reaction of 5-aminoquinoxaline with alkoxymethylene derivatives affords the corresponding quinoxalinoaminoethylenes. These
undergo a thermal cyclization to yield angularly annelated 10H-pyrido[2,3-f]quinoxalines. The structures of all products were deduced from their IR, UV, mass, 1H, and 13C NMR spectra.
Received September 24, 1999. Accepted November 18, 1999 相似文献
20.
Issa Yavari Mehdi Adib Hamid R. Bijanzadeh Majid M. M. Sadegi Hossein Logmani-Khouzani Javad Safari 《Monatshefte für Chemie / Chemical Monthly》2002,133(8):1109-1113
Summary. A dynamic NMR effect is observed in the 13C NMR spectra of anhydrous quinophthalone (quinoline yellow) and its monohydrate in the vicinity of 47°C and 0°C, respectively,
and is attributed to a restricted rotation around the polarized carbon–carbon double bond. The free energy of activation for
this process in anhydrous quinophthalone and the monohydrate is 65±2 and 55±2 kJ · mol−1, respectively, in CDCl3.
Received September 25, 2001. Accepted (revised) November 14, 2001 相似文献